Add ArrayList to another ArrayList in java

Question

I am having the following java code, in which I am trying to copy the ArrayList to another ArrayList.

 ArrayList nodes = new ArrayList

        

Answer 1

Wouldn't it just be a case of:

ArrayList> outer = new ArrayList>();
ArrayList nodeList = new ArrayList();

// Fill in nodeList here...

outer.add(nodeList);

Repeat as necesary.

This should return you a list in the format you specified.